This application claims priority under 35 USC 119 of Japanese Patent Application No. 2000-395620 filed in JPO on Dec. 26, 2000, the entire disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of controlling a startup of an engine. More particularly, the present invention relates to a method of controlling an engine startup in which characteristics of starting up an engine can be improved.
2. Description of the Related Art
In idling control of an electronically controlled diesel engine, usually feedback control of a normal fuel injection quantity is carried out. In this case, every predetermined control timing, a next fuel injection quantity is calculated by adding a proportional term (this term will be also called a P term hereinbelow) and an integral term (this term will be also called an I term hereinbelow) to a basic injection quantity, and an actual injection quantity is successively corrected so as to bring the quantity closer to a target injection quantity.
During an engine startup period, after cranking revolution is started, combustion begins. Revolution of the engine rises up once, and then settles into a predetermined idling revolution number. However, at the same time the cranking begins, the I term starts with zero value, and calculation of addition is carried out every moment. For example, when it is cold, if a cranking period is long, a fuel quantity exceeds a proper quantity at the time combustion starts (the state where ignition occurs), and black smoke is generated. On the other hand, if the cranking period is short (for example, after warmup is carried out), undershooting or/and hunting occurs due to lack of a fuel quantity at the time the engine revolution number settles into the idling revolution number. As stated above, it has been difficult to solve the problem of black smoke together with the problem of undershooting when the engine revolution number settles into the idling revolution number.
It is an object of the present invention to provide a method of controlling an engine startup in which feedback control of fuel injection quantity is performed by adding at least an integral term (I term) to a basic injection quantity of the engine. Further, in this method, an initial integral term, which is used during an engine startup, is determined in advance. Furthermore, in this method, during the engine startup, the integral term is set to be xe2x80x9c0xe2x80x9d until an engine revolution number reaches a startup revolution number, and when the engine revolution number reaches the startup revolution number, the initial integral term is used as the integral term.
The initial integral term is preferably determined on the basis of one of, or both of, a water temperature and an atmospheric temperature.
The startup revolution number is preferably a value higher than a cranking revolution number and lower than a complete combustion revolution number.
The startup revolution number is preferably a value close to, or equal to, an idling revolution number.
Additional objects, aspects, benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention pertains from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings.